Integration and Operation of an Electrically Small Magnetic EZ Antenna With a High-Power Standing Wave Oscillator Source

© 2015 IEEE. The efficacy of the three-dimensional, rectangular magnetic EZ antenna for use with mesoband high-power microwave (HPM) sources has been demonstrated previously. It overcomes the typical bulky and massive impedance-matching components found currently in most HPM systems, making it an attractive option when space is very limited. However, its extremely compact nature presents practical challenges when dealing with extremely high-power sources due to the associated local field enhancements near the feed and the near-field resonant parasitic element. This letter presents a fully integrated, high-voltage source and radiating system that has several improvements in the antenna, source, and power system that have not before been demonstrated. The full system includes a ferroelectric generator, standing wave oscillator source, and electrically small antenna (ka = 0.37) operating at 510 MHz that can be packaged inside a 15-cm-diameter tube. This small diameter results in a quarter-wavelength-diameter ground plane, and the effects of this small ground plane on the radiation characteristics are explored. The development of a pressurized radome allows for operation at 73.6 kV, significantly higher than previous studies

Assessment of heterologous butyrate and butanol pathway activity by measurement of intracellular pathway intermediates in recombinant Escherichia coli

In clostridia, n-butanol production from carbohydrates at yields of up to 76% of the theoretical maximum and at titers of up to 13 g/L has been reported. However, in Escherichia coli, several groups have reported butyric acid or butanol production from recombinant expression of clostridial genes, at much lower titers and yields. To pinpoint deficient steps in the recombinant pathway, we developed an analytical procedure for the determination of intracellular pools of key pathway intermediates and applied the technique to the analysis of three sets of E. coli strains expressing various combinations of butyrate biosynthesis genes. Low expression levels of the hbd-encoded S-3-hydroxybutyryl-CoA dehydrogenase were insufficient to convert acetyl-CoA to 3-hydroxybutyryl-CoA, indicating that hbd was a rate-limiting step in the production of butyryl-CoA. Increasing hbd expression alleviated this bottleneck, but in resulting strains, our pool size measurements and thermodynamic analysis showed that the reaction step catalyzed by the bcd-encoded butyryl-CoA dehydrogenase was rate-limiting. E. coli strains expressing both hbd and ptb-buk produced crotonic acid as a byproduct, but this byproduct was not observed with expression of related genes from non-clostridial organisms. Our thermodynamic interpretation of pool size measurements is applicable to the analysis of other metabolic pathways

OptFlux: an open-source software platform for in silico metabolic engineering

<p>Abstract</p> <p>Background</p> <p>Over the last few years a number of methods have been proposed for the phenotype simulation of microorganisms under different environmental and genetic conditions. These have been used as the basis to support the discovery of successful genetic modifications of the microbial metabolism to address industrial goals. However, the use of these methods has been restricted to bioinformaticians or other expert researchers. The main aim of this work is, therefore, to provide a user-friendly computational tool for Metabolic Engineering applications.</p> <p>Results</p> <p><it>OptFlux </it>is an open-source and modular software aimed at being the reference computational application in the field. It is the first tool to incorporate strain optimization tasks, i.e., the identification of Metabolic Engineering targets, using Evolutionary Algorithms/Simulated Annealing metaheuristics or the previously proposed OptKnock algorithm. It also allows the use of stoichiometric metabolic models for (i) phenotype simulation of both wild-type and mutant organisms, using the methods of Flux Balance Analysis, Minimization of Metabolic Adjustment or Regulatory on/off Minimization of Metabolic flux changes, (ii) Metabolic Flux Analysis, computing the admissible flux space given a set of measured fluxes, and (iii) pathway analysis through the calculation of Elementary Flux Modes.</p> <p><it>OptFlux </it>also contemplates several methods for model simplification and other pre-processing operations aimed at reducing the search space for optimization algorithms.</p> <p>The software supports importing/exporting to several flat file formats and it is compatible with the SBML standard. <it>OptFlux </it>has a visualization module that allows the analysis of the model structure that is compatible with the layout information of <it>Cell Designer</it>, allowing the superimposition of simulation results with the model graph.</p> <p>Conclusions</p> <p>The <it>OptFlux </it>software is freely available, together with documentation and other resources, thus bridging the gap from research in strain optimization algorithms and the final users. It is a valuable platform for researchers in the field that have available a number of useful tools. Its open-source nature invites contributions by all those interested in making their methods available for the community.</p> <p>Given its plug-in based architecture it can be extended with new functionalities. Currently, several plug-ins are being developed, including network topology analysis tools and the integration with Boolean network based regulatory models.</p

Algal Photosynthesis as the Primary Driver for a Sustainable Development in Energy, Feed, and Food Production

High oil prices and global warming that accompany the use of fossil fuels are an incentive to find alternative forms of energy supply. Photosynthetic biofuel production represents one of these since for this, one uses renewable resources. Sunlight is used for the conversion of water and CO2 into biomass. Two strategies are used in parallel: plant-based production via sugar fermentation into ethanol and biodiesel production through transesterification. Both, however, exacerbate other problems, including regional nutrient balancing and the world's food supply, and suffer from the modest efficiency of photosynthesis. Maximizing the efficiency of natural and engineered photosynthesis is therefore of utmost importance. Algal photosynthesis is the system of choice for this particularly for energy applications. Complete conversion of CO2 into biomass is not necessary for this. Innovative methods of synthetic biology allow one to combine photosynthetic and fermentative metabolism via the so-called Photanol approach to form biofuel directly from Calvin cycle intermediates through use of the naturally transformable cyanobacterium Synechocystis sp. PCC 6803. Beyond providing transport energy and chemical feedstocks, photosynthesis will continue to be used for food and feed applications. Also for this application, arguments of efficiency will become more and more important as the size of the world population continues to increase. Photosynthetic cells can be used for food applications in various innovative forms, e.g., as a substitute for the fish proteins in the diet supplied to carnivorous fish or perhaps—after acid hydrolysis—as a complex, animal-free serum for growth of mammalian cells in vitro

Optimization in computational systems biology

Optimization aims to make a system or design as effective or functional as possible. Mathematical optimization methods are widely used in engineering, economics and science. This commentary is focused on applications of mathematical optimization in computational systems biology. Examples are given where optimization methods are used for topics ranging from model building and optimal experimental design to metabolic engineering and synthetic biology. Finally, several perspectives for future research are outlined

Structured decomposition of a multi-snapshot nine-reconstructables Mueller matrix polarimeter

Snapshot channeled polarimeters forgo temporal modulation in favor of modulating polarization information in either space or wavenumber. We have recently introduced methodologies for describing both channeled and partial polarimeters. In this paper,we focus on the nine-reconstructables design, which limits the resolution loss by reducing the number of carriers. The architecture offers a number of favorable trade-offs: a factor of 5.44 increase in spatial bandwidth or a factor of 3.67 increase in spectral bandwidth, for a smaller amount of temporal bandwidth loss as dictated by the number of snapshots taken. The multi-snapshot structured decomposition given here allows one to analytically shape the measured space with optimal noise characteristics and minimum system complexity.A two-snapshot system can measure a premeditated set of 14 reconstructables;we provide the null space for the subset of optimal systems that also achieve better SNR than the baseline single-snapshot system. A three-snapshot system can measure all 16 Mueller elements while offering an overall 26.3% or 50.4% better bandwidth-SNR figure of merit for the spectral and spatial systems, respectively. Finally, four-snapshot systems provide diminishing returns, but may be more implementable

Structured decomposition design of partial Mueller matrix polarimeters

Partial Mueller matrix polarimeters (pMMPs) are active sensing instruments that probe a scattering process with a set of polarization states and analyze the scattered light with a second set of polarization states. Unlike conventional Mueller matrix polarimeters, pMMPs do not attempt to reconstruct the entire Mueller matrix. With proper choice of generator and analyzer states, a subset of the Mueller matrix space can be reconstructed with fewer measurements than that of the full Mueller matrix polarimeter. In this paper we consider the structure of the Mueller matrix and our ability to probe it using a reduced number of measurements. We develop analysis tools that allow us to relate the particular choice of generator and analyzer polarization states to the portion of Mueller matrix space that the instrument measures, as well as develop an optimization method that is based on balancing the signal-to-noise ratio of the resulting instrument with the ability of that instrument to accurately measure a particular set of desired polarization components with as few measurements as possible. In the process, we identify 10 classes of pMMP systems, for which the space coverage is immediately known. We demonstrate the theory with a numerical example that designs partial polarimeters for the task of monitoring the damage state of a material as presented earlier by Hoover and Tyo [Appl. Opt. 46, 8364 (2007)]. We show that we can reduce the polarimeter to making eight measurements while still covering the Mueller matrix subspace spanned by the objects

Proceedings of SPIE - The International Society for Optical Engineering

Recent advancements in channeled spatio-temporal polarization sensor systems have shown potential for improved imaging performance. Lithographic processes now allow for the manufacture of pixelated focal plane arrays with both color and polarization filters applied at the per pixel level. Both Sony and Pau's group at the University of Arizona have demonstrated the manufacture of these hybrid sensors. These new sensors produce spatially channeled hybrid color/polarization systems and crowd the available channel bandwidth space in the Nyquist square. We present a new system design which utilises polarization elements to generate additional temporal carriers, allowing for the separation of color and polarization channels. This separation has the potential to improve the hybrid system performance for certain classes of scene statistics and is analogous to a kind of super-resolution effect similar to a vibrating sensor or using motion for subsampling. The separation can be achieved by varying the polarization sensitive pixels in time, e.g. a rotating half waveplate or an electro-optic polarization element. We show the system design for an existing COTS Sony sensor as well as a design with improved performance over the Sony focal plane array, along with preliminary results on possible system performance

Proceedings of SPIE - The International Society for Optical Engineering

The display of polarimetric imaging data has been a subject of considerable debate. Display strategies range from direct display of the Stokes vector images (or their derivatives) to false color representations. In many cases, direct interpretation of polarimetric image data using traditional display strategies is not intuitive and can at times result in confusion as to what benefit polarimetric information is actually providing. Here we investigate approaches that attempt to augment the s0 image with polarimetric information, rather than directly display it, as a means of enhancing the baseband s0 image. The benefit is that the polarization-enhanced visible or infrared image maintains a familiar look without the need for complex interpretation of the meaning of the polarimetric data, thus keeping the incorporation of polarimetric information transparent to the end user. The method can be applied to monochromatic or multi-band data, which allows color to be used for representing spectral data in multi-or hyper-spectropolarimetric applications. We take a more subjective approach to image enhancement than current techniques employ by simply seeking to improve contrast and shape information for polarized objects within a scene. We find that such approaches provide clear enhancement to the imagery when polarized objects are contained within the scene without the need for complex interpretation of polarization phenomenology